<template>
  <div>
    <router-link
      tag="div"
      to="/"
      v-show="showAbs"
      class="header-abs"
    >
      <div class="iconfont icon-fanhui header-abs-back"></div>
    </router-link>

    <router-link
      to="/"
      v-show="!showAbs"
      class="header-fixed"
      :style="opacityStyle"
    >
      <i class="iconfont icon-fanhui header-fixed-back"></i>
      景点详情
    </router-link>
  </div>
</template>

<script>
  export default {
    name: 'DetailHeader',
    data() {
      return {
        showAbs: true,
        opacityStyle: {
          opacity: 0
        }
      }
    },
    methods: {
      handleScroll() {
        const top = document.documentElement.scrollTop
        if (top > 60) {
          let opacity = top / 140
          opacity = opacity > 1 ? 1 : opacity
          this.opacityStyle = {opacity}
          this.showAbs = false
        } else {
          this.showAbs = true
        }
      }
    },
    mounted() {
      window.addEventListener('scroll', this.handleScroll)
    },
    unmounted() {
      window.removeEventListener('scroll', this.handleScroll)
    }
  }
</script>

<style lang="stylus" scoped>
  @import '~styles/varibles.styl'
  .header-abs
    position: absolute
    left: .2rem
    top: .2rem
    width: .8rem
    height: .8rem
    line-height: .8rem
    border-radius: .4rem
    text-align: center
    background: rgba(0, 0, 0, .8)
    .header-abs-back
      color: #fff
      font-size: .4rem

  .header-fixed
    z-index: 2
    position: fixed
    top: 0
    left: 0
    right: 0
    height: $headerHeight
    line-height: $headerHeight
    text-align: center
    color: #fff
    background: $bgColor
    font-size: .32rem
    .header-fixed-back
      position: absolute
      top: 0
      left: 0
      width: .64rem
      text-align: center
      font-size: .4rem
      color: #fff
</style>
